Matter enclosed in heavy brackets   appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.
1. Technical Field
The subject invention relates to a hose construction. More specifically, the subject invention relates to a hose assembly comprising a polymeric fluorocarbon inner liner having an expanded polyamide outer liner disposed thereabout.
2. Description of the Related Art
Hose assemblies for conveying fuels are well-known in the art. Such assemblies are exposed to a variety of fuel mixtures and fuel additives in addition to extreme engine temperatures. Thus, such hose assemblies must be chemically as well as heat resistant to degradation as a result of chemical and heat exposure.
Polymeric fluorocarbon materials such as polytetrafluoroethylene possess the requisite chemical and temperature resistant properties for most fuel hose applications. Unfortunately, however, polymeric fluorocarbon materials exhibit relatively poor tensile and hoop strengths. As a consequence, such fluorinated materials are prone to kinking. Such kinking remains permanent and provides a continual resistance to fluid flow through the hose assembly. Moreover, as a result of the fluorinated material""s low tensile strength, attachment of securing or coupling members to the hose assembly is unreliable.
Various approaches have been described for offering additional strength to a polymeric fluorocarbon liner. One approach involves braiding fibers about the inner fluorocarbon liner. The braided fibers offer additional strength to the fluorocarbon liner resulting in a hose assembly that resists kinking. An example of such an approach is disclosed in co-pending U.S. Ser. No. 535,734, filed Jun. 11, 1990 and assigned to the assignee of the subject invention. A drawback to such braiding techniques, however, is the extensive labor and time involved.
Additional examples for strengthening an inner fluorocarbon liner with an outer liner are shown in U.S. Pat. No. 2,991,808 to Siegmann, U.S. Pat. No. 4,104,095 to Shaw, and U.S. Pat. No. 4,800,109 to Washizo, all of which disclose the use of a polytetrafluorethylene inner liner supported within an outer liner.
Finally, U.S. Pat. No. 3,547,162 to Schaerer discloses a pipe assembly wherein an inner cross-linked polyolefin liner is supported within an expanded urethane or PVC outer liner.
According to the present invention, there is provided a hose assembly comprising a tubular inner liner and an outer liner disposed about the inner liner. The inner liner comprises a polymeric fluorocarbon material resistant to chemical and heat degradation. The hose assembly is characterized by the outer liner, comprising an expanded polyamide material for increasing the strength of the hose assembly.
Accordingly, the present invention provides a hose assembly including an inner liner having chemical and heat resistant properties and an expanded polyamide outer liner providing support and strength to the inner liner thereby increasing the hose assembly""s hoop and tensile strength. Thus, the present hose assembly is resistant to kinking and possess sufficient strength for allowing the attachment of securing or coupling members thereto.
An advantage of the present hose assembly""s outer liner comprising an expanded polyamide material is a substantial reduction in the weight of the hose assembly while maintaining the necessary hose strength. The present hose assembly""s expanded polyamide outer liner not only provides strength to the hose assembly but also provides ample protection from external heat and chemical degradation at a substantially reduced weight.